   package com.example.demo.repository;

   import com.example.demo.model.User;
   import org.springframework.data.jpa.repository.JpaRepository;
   import org.springframework.stereotype.Repository;

   import java.util.Optional;

   @Repository
   public interface UserRepository extends JpaRepository<User, Long> {
       Optional<User> findByUsername(String username);
   }
   